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<h1><a href="https://archiveofourown.org/works/27094909">Preying on Mercie</a> by <a class='authorlink' href='https://archiveofourown.org/users/tansybells/pseuds/tansybells'>tansybells</a></h1>

<table class="full">

<tr><td><b>Series:</b></td><td>Succubus and Saint [2]</td></tr>

<tr><td><b>Category:</b></td><td>Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses</td></tr>

<tr><td><b>Genre:</b></td><td>Alternate Universe - Succubi &amp; Incubi, Blasphemy, Church Sex, Corruption, F/F, Female My Unit | Byleth, Mercedes is a Beautiful Fat Lady, Porn With Plot, Sex Magic, Succubus Byleth, Tail Sex</td></tr>

<tr><td><b>Language:</b></td><td>English</td></tr>

<tr><td><b>Status:</b></td><td>Completed</td></tr>

<tr><td><b>Published:</b></td><td>2020-10-27</td></tr>

<tr><td><b>Updated:</b></td><td>2020-10-27</td></tr>

<tr><td><b>Packaged:</b></td><td>2021-05-09 03:41:50</td></tr>

<tr><td><b>Rating:</b></td><td>Explicit</td></tr>

<tr><td><b>Warnings:</b></td><td>No Archive Warnings Apply</td></tr>

<tr><td><b>Chapters:</b></td><td>1</td></tr>

<tr><td><b>Words:</b></td><td>6,313</td></tr>

<tr><td><b>Publisher:</b></td><td>archiveofourown.org</td></tr>

<tr><td><b>Story URL:</b></td><td>https://archiveofourown.org/works/27094909</td></tr>

<tr><td><b>Author URL:</b></td><td>https://archiveofourown.org/users/tansybells/pseuds/tansybells</td></tr>

<tr><td><b>Summary:</b></td><td><div class="userstuff">
              <p>The demon Byleth acquiesces to the holy woman's request, if only for promise of payment. When she collects, however, unexpected emotions accompany Mercedes' release.</p>
            </div></td></tr>

<tr><td><b>Relationships:</b></td><td>Mercedes von Martritz/My Unit | Byleth</td></tr>

<tr><td><b>Series:</b></td><td>Succubus and Saint [2]</td></tr>

<tr><td><b>Series URL:</b></td><td>https://archiveofourown.org/series/1977550</td></tr>

<tr><td><b>Comments:</b></td><td>10</td></tr>

<tr><td><b>Kudos:</b></td><td>42</td></tr>

</table>

<a name="section0001"><h2>Preying on Mercie</h2></a>
<div class="story"><div class="fff_chapter_notes fff_head_notes"><b>Author's Note:</b><ul class="associations">
      <li>For <a href="https://archiveofourown.org/users/Spiderlily_Writes/gifts">Spiderlily_Writes</a>.</li>



    </ul></div><div class="userstuff module">
    
    <p>
  <span>Byleth groans into the pillow beneath her face and mumbles something that even she can’t make out in these dark, infernally early mornings that Mercedes </span>
  <em>
    <span>insists </span>
  </em>
  <span>upon appreciating. She’d like nothing more than to return to her pleasant dream, which had been one in which she’d had the delightful opportunity to pleasure a gorgeous blonde woman (that looked nothing whatsoever like the one whose bed she currently occupied,</span>
  <em>
    <span> nothing</span>
  </em>
  <span>!) but no. No.</span>
</p><p>
  <span>Is this it? Is this Byleth’s punishment? Yes, maybe she’s made a habit of ignoring her assigned task in favor of frequently coming back to visit the woman for sex instead of just corrupting her and having it all be over with, but that doesn’tt mean she has to be woken up with such terrible intent. Mercedes had risen like an automaton at the first ringing of the parish’s morning bell, after all, and she seems </span>
  <em>
    <span>determined </span>
  </em>
  <span>to make Byleth enjoy the morning as much as she is.</span>
</p><p>
  <span>“It’s really a beautiful service,” Mercedes says, and Byleth pulls her face away from the pillow to squint at Mercedes, who stands before the small but serviceable mirror that hangs on a wall of her bedroom. After adjusting the way her modest dress sits around her hips and obscures her ample breasts, Mercedes squints at her reflection and adjusts the way her chiffon veil covers her short, fluffy hair. Then, she turns back to smile kindly at Byleth. “You never know. You might like it.”</span>
</p><p>
  <span>Byleth groans again, louder this time, in the hopes that Mercedes will </span>
  <em>
    <span>finally </span>
  </em>
  <span>notice how reluctant she, a succubus, is to pay homage to the Goddess, the staunch and eternal enemy of all demons. She flicks her tail through the air impatiently, but Mercedes is impervious to her plight. It had been a mistake to say that she wouldn’t be harmed by setting foot in a holy place—she is a </span>
  <em>
    <span>sex </span>
  </em>
  <span>demon, after all, not a </span>
  <em>
    <span>demon </span>
  </em>
  <span>demon, and with the apparent exception of Mercedes herself, priests and clergymen and all those other people who were prone to taking vows of celibacy were notoriously good targets.</span>
</p><p>
  <span>Byleth is shaken from her consideration by the sudden creaking of the bed beneath her, and she looks over her shoulder to see that Mercedes has made herself comfortable nearby. Mercedes sits down on the edge of her bed. Byleth bristles as her partner places a soft hand between her shoulder blades.</span>
</p><p>
  <span>“The singing is lovely,” Mercedes continues, ignoring the way Byleth prickles at her touch as she begins to gently rub her palm up and down the bare skin of the demon’s back. It’s only a moment before Byleth relaxes, sinking further into Mercedes’ bed, and Mercedes chuckles warmly. “And when the light hits the stained glass above the altar just right, </span>
  <em>
    <span>oh—</span>
  </em>
  <span>” Mercedes sighs, and Byleth grinds her pointed teeth together. It pisses her off that Mercedes can make that sweet, fluttering little sound while thinking about something other than Byleth and the things they do together. “It’s an absolutely beautiful sight, Byleth. If you won’t come for me, won’t you come for that?”</span>
</p><p>
  <span>Byleth grumbles into the pillow, and in return, the gentle up-and-down motion of Mercedes’ hand on her back turns into a light, teasing running of Mercedes’ nails along her spine.</span>
</p><p>
  <span>“Please, Byleth?” The mattress creaks beneath them as Mercedes leans over Byleth’s nakedness and croons in her ear. “Come to service with me, hmm?”</span>
</p><p>
  <span>But Byleth isn’t listening anymore. Instead, she finds all of her attention dedicated to how Mercedes traces the curve of her spine, making tiny circular motions across her vertebrae, how those tantalizing little circles move lower and lower and lower until they come to the base of her spine, of her tail. Mercedes scratches at the little patch of skin that sits right above where her dark tail meets ashy skin, and those repetitive motions send little shudders of elation shooting up Byleth’s back, down her legs, and straight to where her thighs meet.</span>
</p><p>
  <span>Byleth moans quietly into the pillow at the sensation, and lifts her lower back up in an attempt to press harder against Mercedes’ ministrations. She needs more of that feeling, </span>
  <em>
    <span>craves </span>
  </em>
  <span>it, but instead of giving in to Byleth’s need, Mercedes lifts her hand away entirely.</span>
</p><p>
  <span>“I’ve got to go now,” Mercedes says sweetly. “Or I’m going to be late for church.” With a frown, Byleth flips over onto her back just in time to watch Mercedes stand up from the bed and smooth out the lap of her skirt. She looks over her shoulder to smile graciously at Byleth, at which the succubus can only scowl. Looks like trying to get Mercedes to get a quickie in before church—or better yet, distract her from going to church at all—is out of the question.  </span>
</p><p>
  <span>“You should just stay,” Byleth finally says, a gravelly frustration filling her voice. “No one’ll miss you, anyway, and I think we could have a </span>
  <em>
    <span>much </span>
  </em>
  <span>better time together.” To prove her point, she arches her back off of the bed, effectively presenting her nakedness to Mercedes, and cups the lower halves of her breasts in her palms. Slowly, she drags the pads of her thumbs over her nipples and lets out a quiet, pent-up moan.</span>
</p><p>
  <span>Mercedes is going to see it as a test from her Goddess, she knows. Hang back with the hot demon lady and have another round of the best sex of her life, or be a good little church girl and go to service. And Byleth is well aware of the choice Mercedes is going to make, but she might as well </span>
  <em>
    <span>try </span>
  </em>
  <span>to do her job.</span>
</p><p>
  <span>“Stay with me,” she presses, staring into Mercedes’ baleful blue eyes with all the desperation she can muster. But just as expected, Mercedes tucks a fringe of blonde hair over her ear and leans in to brush a kiss to Byleth’s cheek. She doesn’t immediately straighten up, though, and instead hovers just by Byleth’s ear.</span>
</p><p>
  <span>“Come with me,” Mercedes suggests, </span>
  <em>
    <span>purrs</span>
  </em>
  <span> really, “and I’ll be sure to make it worth your while.” At the warmth of her breath, a chill rolls down Byleth’s spine.</span>
</p><p>
  <span>“Do you promise?” Byleth asks, and Mercedes, pulling back to meet her eyes, nods cheekily.</span>
</p><p>
  <span>“Do you remember what you asked of me, the first night we met?” Mercedes asks in return. Byleth has to think it over for a moment.</span>
</p><p>
  <span>“For your deepest desires,” the demon finally says with a slowly growing smile, “for your darkest, most perverse dreams.” Is Mercedes suggesting what she thinks she’s suggesting? Has she finally begun to have an effect on the surprisingly salacious woman, or is it simply an aspect of Mercedes that she’s incredibly skilled at keeping hidden? Whatever it is...</span>
</p><p>
  <span>“And what did you say you would do with them?”</span>
</p><p>
  <span>Byleth grins now, revealing an unnatural number of too-sharp teeth.</span>
</p><p>
  <span>“That I’ll fulfill them.”</span>
</p><p>
  <span>“Perfect.” Mercedes turns away from Byleth and looks towards the little closet in which she keeps all of her clothing. Byleth groans as Mercedes smiles.</span>
</p><p>
  <span>“Then, how about we find something for you to wear?” her human says. “As accepting as the church is, you need at least </span>
  <em>
    <span>one </span>
  </em>
  <span>piece of clothing on if they’re going to let you in the door.”  </span>
</p><p> </p><hr/><p> </p><p>
  <span>“I don’t get how you </span>
  <em>
    <span>like </span>
  </em>
  <span>all that!”</span>
</p><p>
  <span>Byleth storms into Mercedes’ little room, ripping off all of the stupid clothes Mercedes had covered her up with. The baggy hat that covered up her horns is unceremoniously dumped on the ground, and the stupid swishy pants that Mercedes forced her into go flying through the air, </span>
  <em>
    <span>finally </span>
  </em>
  <span>setting her tail free from its fabric confines.</span>
</p><p>
  <span>“Stupid </span>
  <em>
    <span>fucking</span>
  </em>
  <span> little—”</span>
</p><p>
  <span>Shoes shoot over her head and hit the wall as she kicks them off, one only barely missing Mercedes’ head where she leans against the doorframe. Mercedes only chuckles, apparently unconcerned by the concussive force she’d barely avoided.</span>
</p><p>
  <span>Byleth rolls her eyes, and as soon as she manages to return to her preferred, near-naked state, the succubus whips around to narrow her eyes at Mercedes.</span>
</p><p>
  <span>Was Mercedes </span>
  <em>
    <span>trying </span>
  </em>
  <span>to make her miserable? The church service had been pretty, yes, just as Mercedes had promised, but the whole…</span>
  <em>
    <span> religiousness </span>
  </em>
  <span>underlying it had made Byleth nauseous. Worse, despite all of Byleth’s attempts to distract Mercedes during the service—a surreptitious hand on the thigh slowly sliding up, pulling Mercedes down for a whisper that turned into a nibble on the ear, little things like that—none of it had seemed to be effective.</span>
</p><p>
  <span>If </span>
  <em>
    <span>that’s</span>
  </em>
  <span> the game Mercedes is trying to play, Byleth decides, then perhaps it’s time for her to play along.</span>
</p><p>
  <span>“I didn’t realize clothes would be so—” Mercedes starts to say, but she’s cut off as Byleth stalks towards her with a predatory snarl, grabs the collar of Mercedes’ dress, and yanks her in close to her face. Mercedes’ breath, warm and sweet, washes over the demon, “—disagreeable to you, Byleth.”</span>
</p><p>
  <span>“I put up with it,” Byleth growls with a jerk of her hand, pulling Mercedes close enough that their noses touched at the tips, “because it was part of our </span>
  <em>
    <span>deal. </span>
  </em>
  <span>And you, of all people</span>
  <em>
    <span>, </span>
  </em>
  <span>should know that a devil will always expect her due.”</span>
</p><p>
  <span>Mercedes just smiles, like she’s been expecting exactly this confrontation after the hassle of dragging Byleth to worship and back. “What makes you think I don’t want to pay you back?” she asks with a simple, piteous expression. “I made you a promise, so of course I’ll pay you back.”</span>
</p><p>
  <span>She makes as if to reach out and bridge the gap between her lips and Byleth’s, but Byleth pulls away, unsatisfied. “I don’t want that.”</span>
</p><p>
  <span>“What happened to ‘fulfilling my darkest dreams?’” Mercedes tilts her head to the side, teasing affection dancing in her eyes. “Just tell me.”</span>
</p><p>
  <span>“I plan to.” Byleth curls her upper lip in a snarl. “But not here. Not now.”</span>
</p><p>
  <span>Byleth draws upon her magic with a flick of her hand and a feral grin. Her portal opens up with an almost musical chime; Mercedes’ gaze flickers uncertainly towards the gaping hole in space—and now, time. What Mercedes is going to experience will be unsettling at least, Byleth is well aware of that, and it’s </span>
  <em>
    <span>exactly </span>
  </em>
  <span>what she wants.</span>
</p><p>
  <span>Taking Mercedes’ hand, Byleth guides her through the portal, and her gentle lead is rewarded with a gasp of delight. Or is it horror? Byleth can’t really tell; the two have a tendency to blur together after so many years of existence. Nor can she tell if the tiny squeeze she gives Mercedes’ hand is comforting or not, but she takes pride in the shudder that runs through Mercedes’ body.</span>
</p><p>
  <span>Instead of the warm midmorning light that fills Mercedes’ simple home, their surroundings are lit up by bright, colorful blocks of chilling moonlight that, if they were any further away, would make up a stylized picture of the Goddess. And instead of providing a soft, comfortable bed for Mercedes’ pretty head, Byleth puts her hands on Mercedes’ shoulders and pushes her back onto the very altar before which Mercedes had prayed just a few short hours earlier.</span>
</p><p>
  <span>Byleth crawls up onto the altar, her knees on either side of Mercedes’ hips, and lowers her upper body to press against Mercedes. With her elbows placed above her partner’s shoulders, she leans in close to Mercedes’ face with a wild glint in her eyes. When they’re so close like this, she can feel the quick, warm puffs of Mercedes’ breath against her face, and the terror that surely must be running through Mercedes’ veins by now must be </span>
  <em>
    <span>delicious. </span>
  </em>
  <span>Byleth licks her lips.</span>
</p><p>
  <span>“You said you’d make it worth my while,” she purrs, then she nips at Mercedes’ earlobe with just enough force to break skin. The scent of Mercedes’ blood as it wells up in tiny rubies on her skin, warm and sweet in the chill of the marble church, is nothing short of intoxicating. “And I can’t think of anything else I want more. I want to take you here, now, in the precious hall of your precious </span>
  <em>
    <span>Goddess, </span>
  </em>
  <span>and we’ll see to whom your soul belongs then.” </span>
</p><p>
  <span>Byleth laps up what little blood has surfaced, then lifts herself just enough so that she can see the expression on Mercedes’ face. Just as she hoped, Mercedes has paled at the implications of what Byleth intends to do to her, and Byleth smirks.</span>
</p><p>
  <span>“Isn’t that what you want?” Byleth asks, and Mercedes’ breath catches beneath her as Byleth lifts a hand, walks her fingers across the taut fabric covering Mercedes’ breasts, and runs her thumb along the slightly raised hem of Mercedes’ smallclothes beneath her dress. “You want me to have my way with you, right here, beneath the gaze of your ever-watchful—”</span>
</p><p>
  <span>Mercedes’ hand appears at the back of Byleth’s neck, and before the demon has a chance to react, Mercedes drags her down to crash their lips together hungrily. Byleth grins against Mercedes; Mercedes takes advantage of her delight to slip her tongue into Byleth’s mouth. Her tongue runs against the points and angles of Byleth’s sharp teeth, and in return, Byleth grinds down against Mercedes’ hips.</span>
</p><p>
  <span>With a gasp, Mercedes lets go of Byleth’s neck, which lets Byleth pull back and marvel at the hunger that now shines darkly in Mercedes’ blue eyes.</span>
</p><p>
  <span>“I want you,” Mercedes says between gasps, “to show me the full majesty of Her creation.”</span>
</p><p>
  <span>Byleth groans, unsure whether it’s possible for her to roll her eyes with any more frustration. How long was it going to take before Mercedes figured out that she didn’t have any affiliation with the damn Goddess? Goddess </span>
  <em>
    <span>this, </span>
  </em>
  <span>Goddess </span>
  <em>
    <span>that—</span>
  </em>
  <span>she was so fucking tired of it.</span>
</p><p>
  <span>“I’m not going to do anything of the sort,” Byleth hisses. “What I’m </span>
  <em>
    <span>going </span>
  </em>
  <span>to do, Mercedes, is bring you to the very brink of everything you’ve ever wanted. And by the time I’m done with you, you’ll be praying for </span>
  <em>
    <span>me. </span>
  </em>
  <span>Not your Goddess, </span>
  <em>
    <span>me.</span>
  </em>
  <span>”</span>
</p><p>
  <span>But to accomplish that goal, Mercedes needs to be undressed first. To have her laid bare in the night air, completely exposed to the statues of her Goddess that loom above them, is a thought that sends an excited shudder down Byleth’s spine and a curl to the end of her tail. She looks at the woman laid prostrate beneath her with a critical eye, cocking her head sharply to the side as her gaze roves over the seams and hems that obscure the breadth of Mercedes’ beauty.</span>
</p><p>
  <span>Then, after she lifts her hand and regards it with an intent curiosity, Byleth glances back to the dress getting in her way. She smiles, and Mercedes wriggles beneath her with wide, uncertain eyes. Magic gathers around her hand in a dark, ominous cloud flecked through with silver, and when the cloud dissipates, the human-like nails that she had been sporting up to that point had been replaced with predatory, catlike talons.</span>
</p><p>
  <span>“Are you going to hurt me?” Mercedes gasps, and from the way her cheeks flush with the question, Byleth momentarily wonders if maybe she </span>
  <em>
    <span>should. </span>
  </em>
  <span>But she’s not in the mood to monitor Mercedes for the points at which pain becomes her pleasure, when torture feels like bliss, and she is a little too invested in her current plan to completely dismiss it.</span>
</p><p>
  <span>“I’ve hated this dress since you put it on this morning,” Byleth grumbles as she sets the tip of her index talon at the base of Mercedes’ neck, just above where the neckline of her dress begins. “It was </span>
  <em>
    <span>torture </span>
  </em>
  <span>to sit there through church, knowing that at any moment I could tear through this flimsy fabric and have my way with you.”</span>
</p><p>
  <span>She drags her talon down, and the sharp edge makes its first cut into the simply patterned fabric. “If I wanted to, I could have shown every single other person in those pews just what sort of debauchery and sin that you take part in.” She pairs her words with the paring of Mercedes’ clothes, and centimeter by centimeter, inch by inch, the demon’s prize is revealed.</span>
</p><p>
  <span>Byleth’s tail flicks cheerfully through the air as Mercedes’ cleavage is slowly exposed to the air; she pulls the smooth curve of her talon back up through the gentle furrow between Mercedes’ breasts. “How does it feel, Mercedes?” she asks with a lazy smile as she trails along invisible lines that only she can see, marveling at the light gooseflesh that follows her touch. “How does it feel to know that you’re responsible for the desecration of holy ground?”</span>
</p><p>
  <span>“You seem to think,” Mercedes gasps beneath her, nearly offended, “that I’m </span>
  <em>
    <span>ashamed </span>
  </em>
  <span>of my body.”</span>
</p><p>
  <span>“Far from it.” Byleth yanks her hand down without prelude, slicing through the fabric of Mercedes’ smallclothes. Mercedes squeaks as her fullness of her breasts break free from the shackles of her dress and are exposed to the cold church air. “Your body is a miracle,” Byleth continues with a self-satisfied smirk as she flicks at one of Mercedes’ nipples and makes the woman squeak again. “A miracle that I intend to claim for myself.”</span>
</p><p>
  <span>Mercedes opens her mouth, then closes it and diverts her eyes as Byleth brushes her thumb across her bare nipple with a half-lidded fondness reminiscent of their first encounter with each other. “It—that isn’t how miracles work, Byleth,” Mercedes mumbles, that blush that Byleth had noticed earlier becoming more prominent. “You can’t just give and take like that—”</span>
</p><p>
  <span>“Your Goddess may not be able to,” Byleth interrupts, “but </span>
  <em>
    <span>I </span>
  </em>
  <span>sure as hell can.”</span>
</p><p>
  <span>Byleth glances around her, hoping that some brilliant idea will occur to her in the aftermath of her bold claim. Her tail sways back and forth in the air behind her, the tip flicking with impatience every so often. Then, out of nowhere, a bolt of devilish inspiration strikes her.</span>
</p><p>
  <span>With a too-wide, nearly feline yawn, Byleth nonchalantly drags her claw the rest of the way down Mercedes’ dress, bunching the fabric up in her hands where necessary to make sure that the dress falls away from Mercedes’ body entirely by the time the demon is done with her. Mercedes, to her credit, is familiar enough with the bare nakedness of intimacy that she doesn’t try to cover herself as Byleth cuts through her underwear as well, and she even lifts her hips up off of the altar so that Byleth can pull the shredded fabric out from beneath her.</span>
</p><p>
  <span>When all is said and done, and what remains of Mercedes’ clothes have been tossed aside to be forgotten, Byleth realizes that in her haste to get Mercedes as naked as possible as quickly as possible, she’s left a long, thin, reddening scratch along Mercedes’s body. It travels the valley between Mercedes’ bare breasts, along the gentle rolls of her stomach, and ends just above the dark blonde curls that crown the point where her thighs meet.</span>
</p><p>
  <span>Yet, somehow, Mercedes hadn’t made a single sound.</span>
</p><p>
  <span>Byleth draws away from Mercedes with a wrinkled nose. “Looks like I hurt you after all,” she mutters, dismissing the talons on her hand before running the pad of her finger down the scratch.</span>
</p><p>
  <span>“It wasn’t anything.” Mercedes defends herself, a confident smile gracing her rosebud lips. “I was far more interested in what you were doing.” She hesitates, and that smile turns deliciously shy as she meets Byleth’s eyes. “I… I might still be, actually.”</span>
</p><p>
  <span>In exchange for hearing Mercedes’ readiness, Byleth grins. There’s just something about Mercedes and her ability to make Byleth smile despite her preferred neutrality. Whether it’s because of her kindness, or because of the fun she’s providing Byleth during her long stretches of boredom, though, Byleth can’t really tell. All she knows is that she’s drawn to Mercedes for something more than sex, and while confusing, Byleth isn’t the type to look a gift nun in the mouth. Not when she could be fucking said nun instead.</span>
</p><p>
  <span>With that in mind, she lowers herself down to the base of the scratch. Mercedes’ hair scratches at her chin, ever so slightly, and prompts Byleth to lay her tongue down on the scratch and drag up and away along the line. Mercedes gasps, and trembles beneath her.</span>
</p><p>
  <span>“What are you doing?” she asks quietly, like she’s afraid that speaking with any real volume will alert the Goddess to her presence. Unwilling to answer, Byleth just growls; Mercedes’ breath hitches, but she doesn’t say anything else.</span>
</p><p>
  <span>Undeterred, Byleth traces the line she’d accidentally left behind, picking up any specks of blood that might have welled up as a result of her inadvertent harshness. She swirls her tongue around the dip of Mercedes’ belly button as she travels further and further up Mercedes’ body. Mercedes shudders delightfully beneath her when Byleth reaches the underside of her breast, and instead of continuing between her breasts and along her sternum, Byleth diverts her attention to the nipple itself and latches on with a fierce determination.  </span>
</p><p>
  <span>“Oh, you really like doing that,” Mercedes gasps as Byleth bobs her head up and down, easily shifting back and forth between filling her mouth with Mercedes’ breast and delicately holding the tip of her nipple between her lips. Byleth smiles; Mercedes’ arms snake around her, lightly holding her close as she continues the repetitious up and down, up and down that she’s established. It’s not so much that Byleth likes it as she knows that </span>
  <em>
    <span>Mercedes </span>
  </em>
  <span>likes it, for too often she strives to hold the bulk of her breasts back and refuses to let anyone else appreciate them. Like it’s a sin or something, to appreciate the beauty she’s been blessed with. Or worse, to let anyone </span>
  <em>
    <span>else </span>
  </em>
  <span>appreciate it.</span>
</p><p>
  <span>Namely, Byleth. </span>
  <em>
    <span>Byleth </span>
  </em>
  <span>wants to appreciate it.</span>
</p><p>
  <span>The only issue is, Mercedes </span>
  <em>
    <span>knows </span>
  </em>
  <span>that. She </span>
  <em>
    <span>knows </span>
  </em>
  <span>that Byleth likes paying attention to her chest, so Byleth decides that it’s time to implement phase two of her impromptu plan to completely wreck Mercedes on this altar to the Goddess herself.</span>
</p><p>
  <span>She doesn’t pause her ministrations when she lowers her tail down to where she knows Mercedes’ entrance to be,  nor does Byleth give Mercedes any warning for what’s about to happen. As she circles Mercedes’ breast with her tongue, she mimics that circular motion with the tip of her tail—but this time, around the sensitive nub of Mercedes’ clit. Mercedes’ jaw drops with shock, she opens her mouth to say something, but Byleth detaches from her breast in favor of pushing herself forwards along Mercedes’ body and covering Mercedes’ mouth with her own. Right away, she plunges her tongue into Mercedes’ open mouth. Doing so effectively muffles the cute little sounds that her partner makes, and Byleth takes advantage of the moment to drag the tip of her tail down. Down, across Mercedes’ clit, through folds that the demon is pleased to discover are as wet as they’ve ever been, and Byleth doesn’t stop until she comes across the slightest bit of purchase.</span>
</p><p>
  <span>“Byleth, what—”  </span>
</p><p>
  <span>Mercedes gasps as Byleth drives the tip of her tail against her entrance, wiggling it around to give her a little bit of stretch, before she pushes the whole of the pronged tip in. The high-pitched keen that Mercedes lets loose reminds Byleth, then, that the gentle warmth of a human woman isn’t suited for the sharpness of a succubus’ tail, so she lets her magic warp her tail into something softer, smoother, longer, more conducive to the pleasure she wants to overwhelm Mercedes with.</span>
</p><p>
  <span>“Tell me what you want,” Byleth growls against Mercedes’ lips, even as she strives to muffle the tiny moans the holy woman tries to let free. Everything is amplified in the sacred space of the cathedral, every sound, every shuffling motion, and as tantalizing as the idea of having someone catch Mercedes in the act of desecration is, that isn’t what Byleth came to do. She’s here to prove to Mercedes that for all the power of her Goddess, She’s nothing in the face of raw sexual desire. And judging from the way Mercedes wriggles about on the altar beneath her, Byleth is on her way to success.</span>
</p><p>
  <span>“I—I want—” Mercedes moans against Byleth’s mouth as Byleth draws her tail out slowly, agonizingly, until all that remains is the very tip against her woman’s entrance. “I want—” In lieu of letting Mercedes finish her answer, though, Byleth shoves her tail into Mercedes once again without preamble. What was previously a light embrace tightens as Mercedes grips much harder; her fingers hooking into claws of desperation as she runs her nails down Byleth’s back. “</span>
  <em>
    <span>Byleth</span>
  </em>
  <span>!”</span>
</p><p>
  <span>Byleth arches her back under Mercedes’ nails, her pelvis grinds against her partner’s, and as her control dissipates at the sound of her name falling from Mercedes’ plush lips, she pushes her tail as far into Mercedes as it will go. It’s </span>
  <em>
    <span>her </span>
  </em>
  <span>name that she hears, not that of the Goddess, and Byleth finds her chest heaving with want. She pushes herself off of Mercedes’ torso, and with a birdlike cock of her head, she eyes Mercedes over.</span>
</p><p>
  <span>Mercedes is breathing just as hard as she is, to her smug satisfaction, and instead of looking away from Byleth’s wild gaze with shame, she meets her midway with wide, elated eyes. Her lips are slightly parted as she pants for breath, and Byleth begins pulling in and out of Mercedes to the labored pace with which her chest rises and falls.</span>
</p><p>
  <span>“Byleth, please,” Mercedes whines, and in the colored moonlight that paints her body, Byleth notices tears, like tiny glistening jewels, rolling down from the corners of her eyes.</span>
</p><p>
  <span>“Tell me,” Byleth hisses, leaning in towards Mercedes and speaking against her ear, “could your Goddess bring you so much pleasure? Could She do any—</span>
  <em>
    <span>any </span>
  </em>
  <span>of this for you? Could she—”</span>
</p><p>
  <span>She pulls her tail out from within Mercedes, and forces herself to still. Mercedes trembles beneath her, gasping with want. “Why did you stop?” she asks breathlessly as she tugs down on Byleth, holding her close as blissful tears stain her cheeks. “Byleth—”</span>
</p><p>
  <span>“I want you to tell me,” Byleth says, just as breathless, “that I’m more than your Goddess can ever provide. Could your </span>
  <em>
    <span>Goddess </span>
  </em>
  <span>bring you such pleasure? Could She—”</span>
</p><p>
  <span>“Yes!” Mercedes cries. “She can! She created you, Byleth, and—”</span>
</p><p>
  <span>“That’s not how it works, Mercedes,” Byleth growls, a fierce delight sparking inside her belly at the sight of Mercedes’ conflict. Mercedes’ eyes widen with terror. “You can’t have it both ways. It’s me </span>
  <em>
    <span>or </span>
  </em>
  <span>your Goddess, and if you don’t pick me, I’m going to leave you here, tied up and naked as a whore, and no one will find you until the morning.”</span>
</p><p>
  <span>Mercedes hesitates, her lower lip trembling as her gaze drops away guiltily. Byleth can see her mind working as she considers the ultimatum she’s been presented with, and to sweeten the deal, Byleth swipes the tip of her tail up towards Mercedes’ clit. It’s the lightest of touches, yet Mercedes is so aroused, so </span>
  <em>
    <span>desperate </span>
  </em>
  <span>for her attention that even that briefest tease makes her whole body twitch and Mercedes cries out. Knowing that she has so much sway over this holiest of holy women is positively intoxicating, and it makes the demon want to wrap Mercedes up and keep her for her own.</span>
</p><p>
  <span>“Don’t you remember?” She speaks softly, contrasting the harshness of her conditions with the sweetness of her voice as she looks at Mercedes’ face. “Just think of our companionship, all that we do together. And just think—it could be so much more.”</span>
</p><p>
  <span>The once-steady pattern of Mercedes’ breathing wavers.</span>
</p><p>
  <span>“This doesn’t have to end.” Byleth traces a line from Mercedes’ earlobe to the curve of her jaw. “We can keep going forever and ever, until time itself melts away. Hmm, Mercedes?”</span>
</p><p>
  <span>Mercedes shivers as Byleth’s nail follows along her jaw, and it’s not until Byleth clutches her chin in her hand and forces her to look at her that they finally lock eyes once more. To Byleth’s surprise, the uncertainty and fear that had haunted Mercedes’ gaze since her proposition seems to have disappeared.</span>
</p><p>
  <span>Slowly, either to reward Mercedes for her decision or to punish her once she gives Byleth an answer she doesn’t want to hear, Byleth circles her tail once, twice around Mercedes’ clit before delving  deep into Mercedes once again. She moves in and out, gently in and out, slowly getting Mercedes used to that desperate want once again. She can only imagine the horrible, inescapable pressure that must be building up inside Mercedes at that very moment, so when she brushes up against the very core of Mercedes’ being and Mercedes whimpers again despite her resolution, Byleth smiles.</span>
</p><p>
  <span>Once again, she prompts, “What do you want, Mercedes? Tell me, and I shall make—”</span>
</p><p>
  <span>Mercedes mumbles something; Byleth smiles. What could she possibly be thinking, to be so ashamed of her answer? Byleth is pretty sure she knows exactly what’s on her mind.</span>
</p><p>
  <span>“Louder, sweet one,” she purrs, rubbing Mercedes’ chin with her thumb. “How can I follow your wishes if I can’t hear what you want?”</span>
</p><p>
  <span>Mercedes casts her eyes up towards the statue of the Goddess above them as if in apologetic prayer, her every muscle trembling. Byleth waits, her eyes wide and expectant, and she’s rewarded for her patience as Mercedes meets her eyes once more. It’s impossible for her to tell if the tears that gloss over Mercedes’ eyes are those of shame or of bliss. </span>
</p><p>
  <span>Feeling that she’s close to completion of her goal, Byleth thrusts into Mercedes again. And then, to taunt Mercedes, she stills. “Unless you’d rather pray to your </span>
  <em>
    <span>Goddess</span>
  </em>
  <span> for relief. Maybe </span>
  <em>
    <span>she’ll </span>
  </em>
  <span>manage to make you come.” </span>
</p><p>
  <span>And like a charm, the last vestiges of the resistance that Mercedes has been holding onto completely fall apart like a dam before a flood.</span>
</p><p>
  <span>She clutches Byleth close, her walls clenching around her tail, and cries out, “No, no, she can’t! Just you, Byleth! Please, </span>
  <em>
    <span>please</span>
  </em>
  <span>!”</span>
</p><p>
  <span>Satisfaction, smug contentedness, surges up in Byleth’s chest. She leans to kiss Mercedes deeply, pressing their lips together so solidly that drinking Mercedes down becomes her sole purpose in life. Mercedes gasps against her, sweet and tearful as Byleth recaptures both the rhythm and intensity with which she pounded the end of her tail into her. Mercedes wraps her arms around Byleth’s neck and holds her down tightly, arching her back off of the stone altar upon which she’s laid as she grinds against Byleth’s tail in hopes of achieving that singular, final relief. Her hands wander up to tangle through Byleth’s hair and grab onto the horns mounted there.</span>
</p><p>
  <span>Byleth instinctively jerks away from the unexpected tension on her head, and in doing so, she stops the plunging in-and-outs of her tail in favor of twisting and curling it around within Mercedes, and something about that unexpected motion brings Mercedes to the peak. Mercedes pushes against that brink, Byleth whispers encouragement, and she comes around Byleth with a loud, exuberant cry of relief. Her cry rings out through the church like the resounding chime of wedding bells,</span>
</p><p>
  <span>Waiting patiently for Mercedes to relax enough so that she can slip out of her entrance is a struggle, but for Mercedes’ sake, Byleth does just that. She croons sweet nothings in Mercedes’ ear, kisses away the salty tears that roll down her cheeks, and it’s not until Mercedes’ quiet sobs wither away into the occasional hitch in her breath that Byleth shakes Mercedes’ hands from her head, draws her tail out from within her, and rolls over onto the altar to lie beside her.</span>
</p><p>
  <span>Blinking slowly, Mercedes turns to face Byleth with a thin, weepy smile. She lets her hand fall palm-up between herself and Byleth, an open invitation that Byleth accepts by putting her hand on top.</span>
</p><p>
  <span>“Was that </span>
  <em>
    <span>really </span>
  </em>
  <span>so hard?” Byleth asks with a gentle squeeze to Mercedes’ hand. “We just had sex on the altar of your church. And you didn’t even have to do anything. It was all me.”</span>
</p><p>
  <span>“Don’t tell me that,” Mercedes replies, her voice trembling as though it threatens to break. “If you tell me that, I might mistake it as you saying it’s okay that I let you do that. That I </span>
  <em>
    <span>didn’t </span>
  </em>
  <span>just desecrate the most important place in the church.”</span>
</p><p>
  <span>Byleth laughs mirthfully. “Oh, no, the altar is </span>
  <em>
    <span>definitely </span>
  </em>
  <span>fucked up now. And you and I are the only ones who know about it.”</span>
</p><p>
  <span>Mercedes’ eyes flicker towards the statues of the Goddess looming up above them. Her smile wavers, momentarily, and then fades away entirely. “The Goddess knows, too,” she mumbles as her gaze drops to the stone beneath her. She lets go of Byleth’s hand with a faint frown. The wobble of her breath increases, and Byleth’s heart clenches in panic.</span>
</p><p>
  <span>“Sex is one thing, Byleth.” She closes her eyes, and the tears begin to flow again. “But to denounce the Goddess, who has done so much for me? To </span>
  <em>
    <span>stain </span>
  </em>
  <span>and </span>
  <em>
    <span>defile </span>
  </em>
  <span>the place She has called for us to keep holy for Her?” Byleth sits up as Mercedes slips off of the altar and kneels to pick up her discarded, destroyed clothing. Wrapping her dress around her with all the efficacy of a ruined bedsheet, Mercedes turns back around to face Byleth with a heartbroken expression. “Byleth, I—”</span>
</p><p>
  <span>Silently, Byleth launches herself forward to wrap her arms around Mercedes’ bare shoulders. Mercedes stiffens beneath her, as though she’s waiting for something to be said, but Byleth only buries her face in the curve between Mercedes’ shoulder and neck.</span>
</p><p>
  <span>There’s nothing she </span>
  <em>
    <span>can </span>
  </em>
  <span>say. Her job, her very reason for haunting Mercedes as she does, is to corrupt her, to draw her further and further away from the light with each successive flip of her hair, the seductive sway of her hips, and every single hot-blooded kiss. It’s </span>
  <em>
    <span>her fault </span>
  </em>
  <span>Mercedes is tearing herself up like this, and there’s nothing she can do to soothe the pain she must be feeling.</span>
</p><p>
  <span>Slowly, almost reluctantly, Mercedes’ arms wrap around her waist and she returns Byleth’s impromptu embrace. She leans her head against Byleth’s, and even though Byleth can’t see her face, she can feel the wetness of her tears against her skin.</span>
</p><p>
  <span>“I’ll take you home,” Byleth offers, her voice barely even a whisper. And while it’s their custom by this point, for Byleth to linger at Mercedes’ side until the woman falls asleep, she asks, “Do you want me to stay the night?”  </span>
</p><p>
  <span>It doesn’t surprise her that Mercedes shakes her head, an unspoken ‘no.’ It’s well within her right, considering what Byleth just put her through, but Byleth’s heart aches anyway.</span>
</p><p>
  <span>Demons aren’t supposed to feel for their prey. Humans are supposed to be nothing more than a meal, a source of the sexual energy a succubus needs to survive. Yet Mercedes’ refusal of her companionship hurts more than anything Byleth can imagine, save for the pain that rips through her whenever she imagines the horror of Mercedes telling her to leave forever.</span>
</p><p>
  <span>Slowly, her motions heavy with regret, Byleth opens up the portal. Through the hazy swirl of her magic, she can catch glimpses of the deceptively bland bedroom that Mercedes is going to leave her for, and she frowns. Mercedes straightens up at the sound of Byleth’s magic, and releasing Byleth from her embrace, she moves to step through the portal.</span>
</p><p>
  <span>“Wait!”</span>
</p><p>
  <span>A plea, broken and desperate, cuts through the air between them.</span>
</p><p>
  <span>Mercedes turns back towards Byleth, and as the demon looks down to the human woman’s hand that she hadn’t noticed herself grabbing, she realizes that </span>
  <em>
    <span>she’s </span>
  </em>
  <span>the pitiful source of that desperation. Hurriedly, Byleth drags her eyes up to meet Mercedes’, and she realizes that through an unexpected blur of tears, Mercedes’ smile is piteous, compassionate. Instinctively, Byleth shrivels away from that saintly touch. Her gaze drops to the ground like a millstone, and grabbing her upper arms, she holds herself close.</span>
</p><p>
  <span>“…Sorry.”</span>
</p><p>
  <span>The simple apology is all she can muster, and yet she knows it’s far from enough. Not after all she’s just put Mercedes through. After a few moments pass, she hears Mercedes’ bare footfall against the floor, and assuming that Mercedes has left her, gone through the portal, Byleth looks up.</span>
</p><p>
  <span>Without warning, Mercedes catches Byleth’s chin in her grasp and turns the demon’s head towards her, a shocking reminder of what Byleth had done just a few minutes before. And despite all that she’s just put Mercedes through, Mercedes’ lips are on hers, and she’s being kissed.</span>
</p><p>
  <span>It’s not like Byleth hasn’t kissed before. She’s kissed a million times, and a hundred of them are from that night alone. But there’s no sexuality to Mercedes’ kiss, no deep burning desire that begins to build up in her belly at the touch. Just like Mercedes herself, her kiss is gentle and sweet, but there’s a hardness buried beneath that makes Byleth go weak at the knees.</span>
</p><p>
  <span>When Mercedes finally lets her go, Byleth stumbles back. She catches herself against the stone altar, still reeling from the unexpected kiss, and pressing her hand against her rapidly beating heart, she looks up to Mercedes’ patient expression.</span>
</p><p>
  <span>“I—</span>
  <em>
    <span>what</span>
  </em>
  <span>?” Byleth doesn’t understand. She </span>
  <em>
    <span>can’t </span>
  </em>
  <span>understand, as much as she wants to. She can only hope that her confusion is clear to Mercedes and her beautiful, heartrending smile. “What did you do to me, Mercedes?”</span>
</p><p>
  <span>“I didn’t do anything,” Mercedes says simply, sweetly, sadly as she turns to the portal that Byleth has left open for her. Without another word, she steps through and into her bedroom. The portal fizzles out behind her, and Byleth is left alone.</span>
</p><p>
  <span>Alone with her thoughts, with her uncertainty, and with the frantic beating of her heart.</span>
</p>
  </div><div class="fff_chapter_notes fff_foot_notes"><b>Author's Note:</b><blockquote class="userstuff"><p>Yes, so perhaps this was a gift for the person who beta'd it in the first place, but it's thanks to <a href="https://archiveofourown.org/users/blooming_spiderlily">Lily</a> that there's a sequel at all. And, likely, an inevitable threequel. (Once I figure out how I want these two ladies to resolve, that is.) </p><p>This part in particular is a celebration of Monstertober! I did another piece or two, but most of my excitement has been confined to my <a href="https://twitter.com/tansybells">twitter.</a> As is a lot of Hades hype. That game is so good. </p><p>Thank you for reading. I hope you enjoyed ♡</p></blockquote></div></div>
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